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1 Department of Zoophysiology, University of Aarhus, 131 C. F. Møllers Alle, DK 8000 Aarhus C, Denmark; 2 Clinicum, Laboratorio Automatizado, Iquique, Chile; 3 Biochemistry Department, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium; and 4 Laboratorio de Transporte de Oxígeno, Universidad Cayetano Heredia, Lima 31, Peru
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ABSTRACT |
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 TOP
 ABSTRACT
 INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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In contrast to
birds and mammals, no information appears to be available on the
molecular adaptations for O2 transport in high-altitude
ectothermic vertebrates. We investigated Hb of the aquatic Andean frog
Telmatobius peruvianus from 3,800-m altitude as regards
isoform differentiation, sensitivity to allosteric cofactors, and
primary structures of the 
- and 
-chains, and we carried out
comparative O2-binding measurements on Hb of lowland Xenopus laevis. The three T. peruvianus isoHbs
show similar functional properties. The high O2 affinity of
the major component results from an almost complete obliteration of
chloride sensitivity, which correlates with two -chain
modifications: blockage of the NH2-terminal residues and
replacement by nonpolar Ala of polar residues Ser and Thr found at
position 131(H14) in human and X. leavis Hbs,
respectively. The data indicate adaptive significance of -chain
chloride-binding sites in amphibians, in contrast to human Hb where
chloride appears mainly to bind in the cavity between the -chains.
The findings are discussed in relation to other strategies for
high-altitude adaptations in amphibians.
amphibians; chloride binding; hypoxia; organic phosphates; oxygen transport
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INTRODUCTION |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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HOW IS OXYGEN TRANSPORT to metabolizing tissues secured at high altitude? In contrast to intensive investigations in birds and mammals (7, 39, 59), the molecular strategies for O2 transport in high-altitude ectothermic vertebrates remain unexplored, despite greater variations in environmental conditions (temperature, pH, O2 tension, etc.) and lesser capacities for homeostatic regulation of internal physical and chemical conditions compared with homeothermic vertebrates and a long-standing interest in high-altitude aquatic amphibians (1, 24).
The anuran genus Telmatobius (that variously is referred to as frogs or toads) occurs in the Andes mountains at altitudes from 2,000 to over 4,000 m (14) where aerial O2 tensions fall from ~159 mmHg at sea level to ~92 mmHg. The hypoxic stress is compounded in aquatic species, particularly at night when photosynthetic activity in the ponds ceases (21). T. culeus found in Lake Titicaca at 3,812 m has reduced, poorly developed lungs but exhibits compensatory physiological and behavioral adaptations (24) that include an "oversized," folded skin, which is penetrated by cutaneous capillaries and ventilated by "bobbing" behavior under hypoxia, and small erythrocytes and higher erythrocyte counts, blood-O2 affinities, and O2-carrying capacities than anurans living at sea level (24). Subspecies of Bufo spinulosus living at sea level and at 3,100 to 4,100 m in the Andes analogously exhibit increasing blood-O2 affinities with altitude (43).
The O2 affinity of blood is a product of the intrinsic O2 affinity of the Hb molecules and the erythrocytic effectors that modulate Hb-O2 affinity. Compared with mammals that use 2,3-diphosphoglycerate (DPG) and fish that use ATP (often in conjunction with the more potent effector guanosine triphosphate) (60) as organic O2-affinity modulators, amphibian red cells carry both ATP and DPG in widely varying relative concentrations (22). Moreover, as seen in Rana temporaria (6) and R. catesbeiana (49-51), individual amphibian isoHb components may exhibit functionally significant interactions.
Aiming to identify the molecular adaptations for O2
transport in high-altitude amphibians, we investigated isoHb
differentiation and the interactive effects of pH, temperature,
chloride ions, ATP, and DPG on O2 binding in T. peruvianus Hb, and carried out comparative measurements on Hb from
the lowland aquatic toad Xenopus laevis and determined the
primary structures of the - and -chains of the major T. peruvianus isoHb.
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METHODS |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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Animals, Hb preparation, and isolation. Telmatobius peruvianus of either sex was collected at 3,800-m altitude from small streams near the Andean village Cancosa at the Bolivian boarder in North Chile. Frogs used (n = 5) weighed 17.2 (±2.5) g and measured 4.9 (±0.2) cm (snout-vent). Blood samples were taken within 12 h of descent to the sea level laboratory at Iquique. Electrophoresis on cellulose acetate strips at pH 8.6 indicated Hbs with the same anodic migration rates in all specimens. Specimens of the lowland African clawed toad Xenopus laevis were purchased from Blades Biological, Cowden, UK. Animal handling followed the "Guiding Principles For Research Involving Animals And Human Beings" (2).
Hb purification was carried out at 0-5°C as previously described (61). Hb heterogeneity was investigated by isoelectric focusing in 110-ml LKB columns (Bromma, Sweden) in 0.87% ampholines (pH 6.7-7.7) (46). Separated isoHb fractions were dialyzed against 0.01 M HEPES buffer containing 5×10
4 M EDTA, pH 7.7 (at 5°C) and stored at 
80°C
in 0.1-ml aliquots that were freshly thawed for molecular and
functional characterization. Hemolysates were stripped of organic
phosphates using MB1 mixed ion-exchange resin (BDH Chemicals, Poole, UK).
O2 equilibrium measurements.
O2 equilibria of thin (~0.01 mm) layers of Hb dissolved
in 0.1 M HEPES buffers were measured using a modified diffusion chamber as previously described (57, 58). The P50
[half-saturation O2 tensions (1 mmHg = 0.133 kPa)]
and n50 (cooperativity coefficient at 50%
O2 saturation) values recorded represent individual data points interpolated from Hill plots [log ([OxyHb]/[Hb]) vs. log PO2; correlation coefficient r > 0.995]
that were generated on the basis of at least four equilibration steps
between 30 and 70% O2 saturation. The pH values were
measured in oxygenated subsamples equilibrated to the same temperatures
(61). O2 equilibrium curves focusing on
extreme O2 saturations (<2% and >98%) were analyzed by
end-weighted fitting (61) of the two-state
Monod-Wyman-Changeux (MWC) equation (40) to the data. The
overall heat of oxygenation (
H that includes contributions from
oxygenation-linked reactions) was evaluated from the van't Hoff
equation (4, 63).
Primary structure determinations.
Separation of the - and -chains, enzymatic digestions, and
isolation and amino acid sequence analyses of the peptides were carried
out as previously described (61).
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RESULTS |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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Hb heterogeneity.
Isoelectric focusing revealed one major component, Hb II, and two minor
ones, Hb I and Hb III, with isoelectric points of 7.34, 7.45, and 7.30 and relative abundances of 81:12:7, respectively (Fig.
1). At pH 7.55, T. peruvianus
isoHbs I, II, and III show practically identical P50 values
(Table 1) that correspond with that of
the composite hemolysate (P50 = 7.3 mmHg at 20°C, pH
7.5) (Fig. 1, inset). In conjunction with corresponding
results at pH 7.1 (not shown), this indicates the absence of
functionally significant interactions between the individual isoHbs
under the experimental conditions. Cooperativity in O2
binding at half-saturation (n50) was pronounced
(2.8) and pH independent in Hbs I and II (see Fig. 3) but lower (2.2)
in Hb III.
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Effector sensitivities and allosteric interactions.
Strikingly, the O2 affinity of T. peruvianus Hb
II is almost insensitive to chloride ions, despite pronounced effects
of [ATP + Cl] and [DPG + Cl]
(Figs. 2 and 3 and Table
1). The
potentiation of the Bohr effect by chloride (associated with increased
ionization of the positively charged sites with falling pH) was
correspondingly small (
= 0.16, compared with 0.43 and
0.52, in the presence of Cl, [ATP + Cl], and [DPG + Cl]). The higher
O2 affinities and increased anion sensitivies observed at
10°C than at 20°C (Fig. 3A) reflect exothermic
oxygenation and linked endothermic dissociation of allosteric effactors
that reduce H (Table 1). Hb I showed the same O2
affinity trends as the major component (Hb II) but slightly lower anion
sensitivities (Table 1 and Fig. 3C).
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= 0.40 compared with 0.16 in T. peruvianus) (Fig. 3 and
Table 1).
Dose-response curves (Fig. 4) show that
ATP and DPG exert the same effects on the O2 affinity of
T. peruvianus Hb. The maximum slope of the log
P50 vs. log [phosphate] plots approximates 0.25, tallying
with O2-linked binding of one phosphate molecule per deoxyHb tetramer. The maximum ATP/DPG-induced log P50 shift
is smaller than that for DPG and human Hb (Fig. 4), and the phosphate concentrations required for half the maximum change in log
P50 indicate an apparent dissociation equilibrium constant
in T. peruvianus Hb that is an order of magnitude higher
than for human Hb and DPG (Kd = 7.9×104 compared with 0.71×104 M; Fig.
4).
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G), ATP also decreases
the association constant of the high-affinity relaxed state
(KR) and reduces G (Table 2). However, the
KR values need to be viewed with caution due to
difficulties in measuring the last few percent saturation of the
oxygenation curve (37).
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Primary structure.
The primary structures of the - and -chains of Hb II are shown in
Fig. 6. Whereas the -chain was
directly accessible for Edman degradation, NH2-terminal
sequencing of the intact globin chains showed that the -chain was
blocked. Attempts to deblock the chain failed to give clear-cut
results, so that the four/five NH2-terminal amino acid
residues of this chain are not known. The primary structures of both
globin chains were reconstructed from relevant peptides. Each sequence
was obtained at least twice. The obtained sequences were aligned
unambiguously with known amphibian sequences (Fig. 6).
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-chains that lack the first six NH2-terminal
residues compared with most other vertebrate Hbs (5, 16),
T. peruvianus -chains consist of 145 amino
acid residues. Of these, 93 (64.13%) are identical with X. laevis -1 chains and 87 (56.55%) with human Hb. The
differences in T. peruvianus compared with X. laevis are concentrated in the NH2-terminal region
where only 8 of 24 NH2-terminal -chain residues are
identical. Although common in fish Hbs, acetylation of the -amino
group of the -chains as found in T. peruvianus Hb II is
rare in amphibians and has only been reported in -III larval (56), -III larval (38), and -C chains
(49) of R. catesbeiana.
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DISCUSSION |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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The hypoxic challenge at altitude where O2 loading may
be critical is compounded in aquatic habitats, as indicated by
increased blood-O2 affinities encountered in lowland
amphibians with increasing reliance on water as the respiratory medium
(32) and the higher blood-O2 affinities in
predominantly aquatic T. culeus and X. laevis
than in predominantly terrestrial Rana and
Chiromantis species (Fig.
7A). These interspecies
correlations are in accordance with observations that hypoxic exposure
increases blood-O2 affinity by decreasing red cell DPG
levels in the salamander Ambystoma tigrinum
(66) and raises plasma catecholamine levels [that may increase O2 affinity through red cell swelling (29,
42)] in the toad Bufo marinus (3).
However, 10- to 11-day hypoxic acclimation did not change
blood-O2 affinity in the salamander Desmognathus quadramaculatus (36).
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The ATP-induced Hb-O2 affinity shifts (Fig. 2) and the
difference in affinities between stripped Hb and whole blood in
T. peruvianus and X. laevis (Fig. 7B)
reveal pronounced capacities for effector modulation in both species.
The similar effects of ATP and DPG on the O2 affinity of
T. peruvianus Hb (Fig. 4) tally with similar magnitudes of
ATP- and DPG-binding constants in human Hb (25) and
suggest that the differences in erythrocytic NTP/DPG ratios [~3.0
and ~0.8, respectively, in Lake Titicaca T. culeus and
X. laevis (22)] do not contribute to the
species differences in blood-O2 affinity. The observation
that ATP alone decreases the O2 affinity of T. peruvianus Hb slightly more than ATP + Cl (Fig.
3) may be attributed to competition of the two anions for the same
sites in the central cavity (19, 44) and neutralization of
the positively charged phosphate-binding sites by chloride.
The anuran Hbs show distinctive structure-function relationships.
Compared with human Hb, T. peruvianus Hb II shows a less tight binding of ATP and DPG (Fig. 4), despite conservation of the
positively charged organic phosphate-binding sites in the cavity
between the -chains, e.g., NH2-terminal Val,
2(NA2)His, 82(EF6)Lys, and 143(H21)Lys, which replaces
histidine in human Hb. In X. laevis, the deletion of the
first -chain residue (Fig. 6) could bring the
NH2-terminus closer to the bound cofactor and preserve
phosphate sensitivity despite the loss of His(NA2). The Bohr effect of
the stripped T. peruvianus Hb II is small despite the
presence of 146His(HC3) and a negatively charged residue (Glu) in
position 94(FG1) that contribute about half of the anion-independent Bohr effect in human Hb (30, 47). In contrast to the
majority of vertebrate Hbs, where allosteric effectors decrease the
affinity of the T state of the deoxygenated molecule (53, 54,
62), frog Hbs may also be modulated in the R state, as evident
from the ATP sensitivity of T. peruvianus Hb II (Fig. 4 and
Table 2) and the pH effect in Rana temporaria Hb
(6). The molecular mechanism underlying these effects must
await the elucidation of the crystal structures of deoxy and oxy forms
of amphibian Hbs.
The similar O2 affinities in Hbs I, II, and III and in the stripped hemolysate (Table 1 and Fig. 1) indicate the absence of functionally significant interactions between the individual isoHbs under the tested conditions. This contrasts with R. catesbiana where aggregation of the major tetrameric components B and C to form a low-affinity BC2 trimer-of-tetramers is manifested at corresponding pH and Hb concentrations as tested here (50, 51).
What, if any, are the distinguishing molecular adaptations to altitude
in T. peruvianus Hb? Comparison with lowland
X. laevis Hb shows that the major difference resides with
the effects of anions. Although stripped Hbs from the two species show
almost identical O2 affinities and pronounced [ATP + Cl] effects, T. peruvianus Hb shows a
drastically suppressed chloride sensitivity (log
P50 = 0.10 compared with 0.32 in X. laevis
and >0.4 in human Hb; Figs. 2 and 7B). In the absence of
other changes, this will enhance O2 loading under hypoxia
without the need for reducing erythrocytic organic phosphate levels and
thus allosteric regulatory capacity. In contrast to short-term hypoxic
challenges that evoke adaptive changes in erythrocytic phosphate levels
(41), obligate residence at high altitude appears to be
associated with the presence of high-affinity (iso)Hbs, as previously
illustrated in homeothermic vertebrates. However, in contrast to the
bar-headed goose and Rüppell's griffon (8, 13, 45)
that may fly at 9,000 and 11,300 m above sea level, where the high
intrinsic O2 affinity is attributed to amino acid
substitutions located at the 11- or
12-interface (26, 33, 63)
and llama Hbs, where high blood affinity is achieved through loss of
-chain phosphate-binding residues, the high affinity in T. peruvianus Hb II results from a loss of anion sensitivity that
correlates with -subunit amino acid substitutions.
Two schools of thought exist as regards O2-linked chloride
binding to human Hb, which has been proposed to occur either at "localized" (19) or at "delocalized"
(44) sites. The "localized" binding sites are an
-chain site [lying between the 1Val-NH3+
group and -OH of 131(H14)Ser and the side chain of
131Ser(H14)] and a -chain site (between 1Val and the
-NH3+ group of 82Lys) (47).
Evidence for their involvement comes from X-ray diffraction studies of
crystallized human Hb specifically carboxymethylated at 1Val
(18) and the crystal structure of the human Hb mutant (V1M+H2) [where 1Val(NA1) is exchanged for Met and 2(NA2)His
is deleted], which document the implication of the
NH2-terminal residues in O2 linked chloride
binding and the chloride-dependent Bohr effect (19). The
"delocalized" mechanism proposed by Perutz et al. (44)
builds on the view (10) that excess positive charges in
the water-filled cavity between the -chains destabilize the T state
and that chloride ions diffusing into the cavity of deoxygenated human
Hb reduce O2 affinity by partially neutralizing the
repulsion between these charges, thus reducing the free energy of the T
structure. This mechanism is supported by observations that amino acid
substitutions that increase central cavity electropositivity cause a
proportional increase in O2 affinity and vice versa
(44).
Whereas the mechanism of chloride binding in human Hb remains
unresolved, our data indicate predominant importance of specific ("localized") -chain sites in amphibian Hbs. Thus, the -chain residues (1Val and 131Ser in humans) are conserved in X. laevis Hb (where polar Ser at 131 is substituted by polar Thr and
the NH2-terminal residues are free), which shows pronounced
chloride sensitivity, but eliminated in T. peruvianus Hb
(where 131 is occupied by nonpolar Ala and the -chain
NH2-termini are acetylated), which shows strongly reduced
chloride sensitivity. That chloride may additionally bind in the
central cavity between the -chains (in competition with organic
phosphates) is indicated by the observation that ATP alone has a
greater effect on O2 affinity of T. peruvianus Hb than ATP in the presence of 0.1 M chloride (Fig. 3).
In contrast to evidence for "localized" chloride binding, there is
no evidence from the central cavity amino acid exchanges for greater
"delocalized," oxygenation-linked chloride binding in X. laevis than in T. peruvianus Hb. Perutz et al.
(44) list 5 -chain and 14 -chain polar residues in
the central cavity of human Hb that may affect O2 affinity
by increasing or reducing the excess positive charge. Compared with
X. laevis Hb, T. peruvianus Hb II
shows one -chain and six -chain exchanges at these positions. These are (the helix notation refers to human Hb): 133(H16)Ser
Gly (that represents loss of a polar site), Val inserted at 1(NA1) (that does not affect charge), 2(NA2)GlyHis (that increases positive charges), 104(G6)LysVal (that reduces positive charge), 135(H13)AspGly (that reduces negative charge and thus increases net positive charge), and 101(G3)LeuAla, 132(H10)HisLys,
and 136(H14)AlaGly (that are electroneutral). Assuming
equivalence of structural factors, these exchanges may thus be expected
to increase the number of positive charges in the central cavity and
consequently the intrinsic O2 affinity and the chloride
effect in T. peruvianus compared with X. laevis Hb. Such effects are not evident from our data.
Other evidence indicates that "localized," -chain chloride
binding may also be implicated in adaptations encountered in some mammalian Hbs. The high O2 affinities of Hb from Andean
camellid vicuna (31) and of embryonic pig Hbs Gower I
and Heide I that have 
-(-type) chains (64) are
associated with a 130AlaThr replacement, which introduces a
hydroxyl group that may interfere with chloride binding at neighboring
131Ser. Also, the almost complete lack of chloride effects in human
embryonic Hbs Gower I and Portland (22
and 2
2) (68) correlates with
an analogous 131Ser131Val substitution to that here reported
for T. peruvianus Hb II.
In conclusion, this study shows a novel molecular mechanism for
high-altitude adaptation in ectotherm vertebrates that involves a
reduction in chloride modulation of Hb-O2 affinity via loss of specific chloride-binding sites on the -chains and still allows for phosphate modulatory capacity. It should, however, be borne in mind
that the molecular adaptations supporting tissue O2 supply are but part of a symphony of organismic, cellular, and molecular adjustments expressed in high-altitude animals (39, 63).
As has become well established, hypoxia elicits a fall in (preferred) body temperature, which in anurans, appears to be adenosine and lactate
mediated (11, 12, 67). The low body temperatures that are
naturally experienced by Telmatobius living in cold streams of melted snow impart a range of possible advantages. Apart from raising the O2 content of the water, low temperature
increases blood-O2 affinity, as dictated by the exothermic
nature of the Hb-oxygenation reaction. Also, it decreases metabolic
rate and lowers tissue O2 demands, which in cold-submerged
Rana temporaria are associated with increased reliance on
carbohydrate metabolism and maintenance of homeostatic ATP levels
(17). Hypoxia may, however, also have beneficial effects
under certain conditions (48). Several studies show that
O2 deprivation may protect tissues of homeo- as well as
ectothermic vertebrates against subsequent hypoxic/ischemic
episodes (15, 20, 34). In Rana pipiens and
goldfish, anoxic exposure moreover induces changes in the antioxidant
system that minimize subsequent effects of oxidative stress (23,
34). Telmatobius may be an excellent model for studying adaptations to chronic hypoxemia.
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ACKNOWLEDGEMENTS |
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We thank A. Bang (Aarhus) for valuable technical assistance.
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FOOTNOTES |
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This work was supported by the Danish Natural Science Research Council and the Fund for Scientific Research Projects, Flanders, Belgium.
Address for reprint requests and other correspondence: R. E. Weber, Dept. of Zoophysiology, Univ. of Aarhus, 131 C. F. Møllers Alle, DK 8000 Aarhus C, Denmark (E-mail: roy.weber{at}biology.au.dk).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
August 22, 2002;10.1152/ajpregu.00292.2002
Received 23 May 2002; accepted in final form 9 July 2002.
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REFERENCES |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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|---|
1.
Allen, WR.
Notes on the Andean frog Telmatobius culeus (Garman).
Copeia
1922:
52-54,
1922.
2.
American Physiological Society.
Guiding Principles For Research Involving Animals And Human Beings.
Am J Physiol Regul Integr Comp Physiol
283:
R281-R283,
2002.
3.
Andersen, JB,
Jensen FB,
and
Wang T.
Effects of temperature and oxygen availability on circulating catecholamines in the toad Bufo marinus.
Comp Biochem Physiol A Physiol
129:
473-486,
2001.
4.
Antonini, E,
and
Brunori M.
Hemoglobin and Myoglobin in their Reactions with Ligands. Amsterdam: North-Holland, 1971.
5.
Baldwin, TO,
and
Riggs A.
The hemoglobins of the bullfrog, Rana catesbeiana. Partial amino acid sequence of the chain of the major adult component.
J Biol Chem
249:
6110-6118,
1974.
6.
Bårdgard, A,
Fago A,
Malte H,
and
Weber RE.
Oxygen binding and aggregation of hemoglobin from the common European frog, Rana temporaria.
Comp Biochem Physiol B Biochem Mol Biol
117:
225-231,
1997.
7.
Bartels, H,
Hilpert P,
Barbey K,
Betke K,
Riegel K,
Lang EM,
and
Metcalfe J.
Respiratory functions of blood of the yak, llama, camel, Dybowski deer, and African elephant.
Am J Physiol
205:
331-336,
1963.
8.
Bauer, C,
Rollema HS,
Till HW,
and
Braunitzer G.
Phosphate binding by llama and camel hemoglobin.
J Comp Physiol
136:
67-70,
1980.
9.
Benesch, RE,
and
Benesch R.
The mechanism of interaction of red cell organic phosphates with hemoglobin.
In: Advances in Protein Chemistry, edited by Anfinsen CB,
Edsall JT,
and Richards FM.. New York: Academic, 1974, vol. 28, p. 211-237.
10.
Bonaventura, C,
and
Bonaventura J.
Anionic control of hemoglobin function.
In: Biochemical and Clinical Aspects of Hemoglobin Abnormalities, edited by Caughey WS.. New York: Academic, 1978, p. 647-663.
11.
Branco, LG,
and
Steiner AA.
Central thermoregulatory effects of lactate in the toad Bufo paracnemis.
Comp Biochem Physiol A Physiol
122:
457-461,
1999.
12.
Branco, LG,
Steiner AA,
Tattersall GJ,
and
Wood SC.
Role of adenosine in the hypoxia-induced hypothermia of toads.
Am J Physiol Regul Integr Comp Physiol
279:
R196-R201,
2000.
13.
Braunitzer, G,
Schrank B,
Stangl A,
and
Bauer C.
Regulation of respiration at high altitudes and its molecular interpretation: the sequence of -chains of hemoglobins from pig and llama.
Hoppe-Seyler's Z Physiol Chem
358:
921-925,
1977.
14.
Cei, JM.
Batracios de Chile. Santiago de Chile:: Universidad de Chile, 1962.
15.
Chang, J,
Knowlton AA,
and
Wasser JS.
Expression of heat shock proteins in turtle and mammal hearts: relationship to anoxia tolerance.
Am J Physiol Regul Integr Comp Physiol
278:
R209-R214,
2000.
16.
Chauvet, JP,
and
Acher R.
Phylogeny of hemoglobins. Chain of frog (Rana esculenta) hemoglobin.
Biochemistry
11:
916-927,
1972.
17.
Donohoe, PH,
and
Boutilier RG.
The protective effects of metabolic rate depression in hypoxic cold submerged frogs.
Respir Physiol
111:
325-336,
1998.
18.
Fantl, WJ,
Di Donato A,
Manning JM,
Rogers PH,
and
Arnone A.
Specifically carboxymethylated hemoglobin as an analogue of carbamino hemoglobin. Solution and X-ray studies of carboxymethylated hemoglobin and X-ray studies of carbamino hemoglobin.
J Biol Chem
262:
12700-12713,
1987.
19.
Fronticelli, C,
Pechik I,
Brinigar WS,
Kowalczyk J,
and
Gilliland GL.
Chloride ion independence of the Bohr effect in a mutant human hemoglobin (V1M+H2deleted).
J Biol Chem
269:
23965-23969,
1994.
20.
Gamperl, AK,
Todgham AE,
Parkhouse WS,
Dill R,
and
Farrell AP.
Recovery of trout myocardial function following anoxia: preconditioning in a non-mammalian model.
Am J Physiol Regul Integr Comp Physiol
281:
R1755-R1763,
2001.
21.
Garey, WF,
and
Rahn H.
Gas tensions in tissues of trout and carp exposed to diurnal changes in oxygen tension of the water.
J Exp Biol
52:
575-582,
1970.
22.
Hazard, ES,
and
Hutchison VH.
Distribution of acid-soluble phosphates in the erythrocytes of selected species of amphibians.
Comp Biochem Physiol [A]
73A:
111-124,
1982.
23.
Hermes-Lima, M,
and
Storey KB.
Relationship between anoxia exposure and antioxidant status in the frog Rana pipiens.
Am J Physiol Regul Integr Comp Physiol
271:
R918-R925,
1996.
24.
Hutchison, VH,
Haines HB,
and
Engbretson G.
Aquatic life at high altitude: respiratory adaptations in the Lake Titicaca frog, Telmatobius culeus.
Respir Physiol
27:
115-129,
1976.
25.
Imai, K.
Allosteric Effects in Haemoglobin. Cambridge: Cambridge Univ. Press, 1982.
26.
Jessen, TH,
Weber RE,
Fermi G,
Tame J,
and
Braunitzer G.
Adaptation of bird hemoglobins to high altitudes: demonstration of molecular mechanism by protein engineering.
Proc Natl Acad Sci USA
88:
6519-6522,
1991.
27.
Johansen, K,
Lykkeboe G,
Kornerup S,
and
Maloiy GMO
Temperature insensitive O2 binding in blood of the tree frog Chiromantis petersi.
J Comp Physiol
136:
71-76,
1980.
28.
Jokumsen, A,
and
Weber RE.
Haemoglobin-oxygen binding properties in the blood of Xenopus laevis, with special reference to the influences of aestivation and of temperature and salinity acclimation.
J Exp Biol
86:
19-37,
1980.
29.
Kaloyianni, M,
and
Rasidaki A.
Adrenergic responses of R. ridibunda red cells.
J Exp Zool
276:
175-185,
1996.
30.
Kilmartin, JV.
The alkaline Bohr effect of human hemoglobin.
Ann NY Acad Sci
241:
465-471,
1974.
31.
Kleinschmidt, T,
März J,
Jürgens KD,
and
Braunitzer G.
Interaction of allosteric effectors with -globin chains and high altitude respiration in mammals. The primary structure of two tylopod hemoglobins with high oxygen affinity: vicuna (Lama vicugna) and alpaca (Lama pacos).
Biol Chem
367:
153-160,
1986.
32.
Lenfant, C,
and
Johansen K.
Respiratory adaptations in selected amphibians.
Respir Physiol
2:
247-260,
1967.
33.
Liu, XZ,
Li SL,
Jing H,
Liang YH,
Hua ZQ,
and
Lu GY.
Avian haemoglobins and structural basis of high affinity for oxygen: structure of bar-headed goose aquomet haemoglobin.
Acta Crystallogr A
57:
775-783,
2001.
34.
Lushchak, VI,
Lushchak LP,
Mota AA,
and
Hermes-Lima M.
Oxidative stress and antioxidant defenses in goldfish Carassius auratus during anoxia and reoxygenation.
Am J Physiol Regul Integr Comp Physiol
280:
R100-R107,
2001.
35.
Lykkeboe, G,
and
Johansen K.
An O2-Hb "paradox" in frog blood? (n-values exceeding 40).
Respir Physiol
35:
119-127,
1978.
36.
Maginniss, LA,
and
Booth DT.
Hemoglobin function in a skin-breathing aquatic salamander, Desmognathus quadramaculatus.
Respir Physiol
99:
233-240,
1995.
37.
Marden, MC,
Kister J,
Poyart C,
and
Edelstein SJ.
Analysis of hemoglobin oxygen equilibrium curves. Are unique solutions possible?
J Mol Biol
208:
341-345,
1989.
38.
Maruyama, T,
Watt KWK,
and
Riggs A.
Hemoglobins of the tadpole of the bullfrog, Rana catesbeiana. Amino acid sequence of the chain of a major component.
J Biol Chem
255:
3285-3293,
1980.
39.
Monge, C,
and
Leon-Velarde F.
Physiological adaptation to high altitude: oxygen transport in mammals and birds.
Physiol Rev
71:
1135-1172,
1991.
40.
Monod, J,
Wyman J,
and
Changeux JP.
On the nature of allosteric transitions: a plausible model.
J Mol Biol
12:
88-118,
1965.
41.
Nikinmaa, M.
Membrane transport and control of hemoglobin-oxygen affinity in nucleated erythrocytes.
Physiol Rev
72:
301-321,
1992.
42.
Nikinmaa, M.
Haemoglobin function in vertebrates: evolutionary changes in cellular regulation in hypoxia.
Respir Physiol
128:
317-329,
2001.
43.
Ostojic, H,
Monge C,
and
Cifuentes V.
Hemoglobin affinity for oxygen in three subspecies of toads (Bufo sp.) living at different altitudes.
Biol Res
33:
5-10,
2000.
44.
Perutz, MF,
Shih DT,
and
Williamson D.
The chloride effect in human haemoglobin. A new kind of allosteric mechanism.
J Mol Biol
239:
555-560,
1994.
45.
Piccinini, M,
Kleinschmidt T,
Jürgens KD,
and
Braunitzer G.
Primary structure and oxygen-binding properties of the hemoglobin from guanaco (Lama guanacoe, Tylopoda).
Biol Chem
371:
641-648,
1990.
46.
Qvist, J,
Weber RE,
and
Zapol WM.
Oxygen equilibrium properties of blood and hemoglobin of fetal and adult Weddell seals.
J Appl Physiol
50:
999-1005,
1981.
47.
Riggs, AF.
The Bohr effect.
Annu Rev Physiol
50:
181-204,
1988.
48.
Scholz, H.
Adaptational responses to hypoxia.
Am J Physiol Regul Integr Comp Physiol
282:
R1541-R1543,
2002.
49.
Smith, DJ,
Zhu H,
Kolatkar PR,
Tam L,
Baldwin TO,
Roe BA,
Broyles RH,
and
Riggs AF.
The hemoglobins of the bullfrog, Rana catesbeiana. The cDNA-derived amino acid sequences of the chains of adult hemoglobins B and C: their roles in deoxygenation-induced aggregation.
J Biol Chem
268:
26961-26971,
1993.
50.
Tam, LT,
Manning D,
Cox DJ,
and
Riggs AF.
The hemoglobins of the bullfrog, Rana catesbeiana. Deoxygenation-linked association of tetrameric components B and C to form the trimer BC2: sedimentation analysis and oxygen equilibria.
J Biol Chem
268:
26972-26977,
1993.
51.
Tam, LT,
and
Riggs AF.
Oxygen binding and aggregation of bullfrog hemoglobin.
J Biol Chem
259:
2610-2616,
1984.
52.
Tazawa, H,
Mochizuki M,
and
Piiper J.
Blood oxygen dissociation curve of the frogs Rana catesbeiana and Rana brevipoda.
J Comp Physiol [B]
129:
111-114,
1979.
53.
Tyuma, I,
Imai K,
and
Shimizu K.
Analysis of oxygen equilibrium of hemoglobin and control mechanism of organic phosphates.
Biochemistry
12:
1491-1498,
1973.
54.
Tyuma, I,
kamigawara Y,
and
Imai K.
pH dependence of the shape of the hemoglobin-oxygen equilibrium curve.
Biochim Biophys Acta
310:
317-320,
1973.
55.
Tyuma, I,
Shimizu K,
and
Imai K.
Effect of 2,3-diphosphoglycerate on the cooperativity in oxygen binding of human adult hemoglobin.
Biochem Biophys Res Commun
43:
423-428,
1971.
56.
Watt, KW,
Maruyama T,
and
Riggs A.
Hemoglobins of the tadpole of the bullfrog, Rana catesbeiana. Amino acid sequence of the chain of a major component.
J Biol Chem
255:
3294-3301,
1980.
57.
Weber, RE.
Cationic control of O2 affinity in lugworm erythrocruorin.
Nature
292:
386-387,
1981.
58.
Weber, RE.
Use of ionic and zwitterionic (Tris/BisTris and HEPES) buffers in studies on hemoglobin function.
J Appl Physiol
72:
1611-1615,
1992.
59.
Weber, RE.
Hemoglobin adaptations to hypoxia and altitude-The phylogenetic perspective.
In: Hypoxia and the Brain (Proceedings of the 9th International Hypoxia Symposium, Lake Louise, Canada), edited by Sutton JR,
Houston CS,
and Coates G.. Burlington, VT: Queen City, 1995, p. 31-44.
60.
Weber, RE.
Adaptations for oxygen transport: lessons from fish hemoglobins.
In: Hemoglobin Function in Vertebrates, Molecular Adaptation in Extreme and Temperate Environments, edited by di Prisco G,
Giardina B,
and Weber RE.. Milan, Italy: Springer-Verlag, 2000, p. 23-37.
61.
Weber, RE,
Fago A,
Val AL,
Bang A,
Van Hauwaert ML,
Dewilde S,
Zal F,
and
Moens L.
Isohemoglobin differentiation in the bimodal-breathing Amazon catfish Hoplosternum littorale.
J Biol Chem
275:
17297-17305,
2000.
62.
Weber, RE,
Jensen FB,
and
Cox RP.
Analysis of teleost hemoglobin by Adair and Monod-Wyman-Changeux models. Effects of nucleoside triphosphates and pH on oxygenation of tench hemoglobin.
J Comp Physiol
157B:
145-152,
1987.
63.
Weber, RE,
Jessen TH,
Malte H,
and
Tame J.
Mutant hemoglobins (119-Ala and 55-Ser): functions related to high-altitude respiration in geese.
J Appl Physiol
75:
2646-2655,
1993.
64.
Weber, RE,
Kleinschmidt T,
and
Braunitzer G.
Embryonic pig hemoglobins Gower I (Z22), Gower II (22), Heide I (Z2v2) and Heide II (2v2 ): oxygen-binding functions related to structure and embryonic oxygen supply.
Respir Physiol
69:
347-357,
1987.
65.
Wells, RMG,
and
Weber RE.
Fixed acid and carbon dioxide Bohr effects as functions of hemoglobin-oxygen saturation and intra-erythrocytic pH in the blood of the frog, Rana temporaria.
Pflügers Arch
403:
7-12,
1985.
66.
Wood, SC,
Hoyt RW,
and
Burggren WW.
Control of hemoglobin function in the salamander, Ambystoma tigrinum.
Mol Physiol
2:
263-272,
1982.
67.
Wood, SC,
and
Malvin GM.
Physiological significance of behavioral hypothermia in hypoxic toads (Bufo marinus).
J Exp Biol
159:
203-215,
1991.
68.
Zheng, T,
Zhu Q,
and
Brittain T.
Origin of the suppression of chloride ion sensitivity in human embryonic hemoglobin Gower II.
IUBMB Life
48:
435-437,
1999.
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, Absorption values at 540 nm;
, pH at 25°C. Horizontal bars show fractions pooled
for analyses. Right inset: diagram of column at the end of
focusing. Left inset: O2 equilibrium curves of
, Hb I;
, Hb II; 
).
Buffer, 0.1 HEPES; [Heme], 0.15 mM (Hb II); ATP/Hb ratio: >100.
, Cl
, ATP + Cl
,
2,3-diphosphoglycerate (DPG) + Cl
, 
